UnitedHealth Group Inc. (UNH) - Get Report  again raised its outlook for 2017 net earnings to between $9.20 to $9.35 per share and adjusted net earnings to a range of $9.75 to $9.90 per share based on performance through the first-half of 2017, the company said as it reported second-quarter earnings Tuesday.

The insurer similarly boosted guidance when first-quarter numbers were announced in March.

UnitedHealth shares were up in pre-market trading Tuesday but fell when the market opened. By the end of the day, however they were up slightly, rising 21 cents to $186.85.

Jefferies LLC analyst David Windley argued that investors had already calculated in a second-quarter earnings beat and were possibly underwhelmed by the slight improvement over previous guidance. "This modest beat and raise probably translates into a flattish reaction today," he wrote in a note after UnitedHealth's numbers were released.

Windley also suggested that investors may also have been discouraged by UnitedHealth's failure to confirm a July 7 Bloomberg report that the insurer was close to buying the health unit of Advisory Board Co. ABCO. 

Mizuho Securities USA Inc.'s Sheryl Skolnick was more impressed with UnitedHealth's performance, particularly because of the insurer's ability to control its medical loss ratio (MLR), which she said beat the Wall Street consensus by a "whopping" 50 basis points.

"Everything was really good—but the MLR is our focus as we think that this is where all the investment [UnitedHealth] has made in transforming health care is finally coming to fruition in a way the Street knows exactly how to value."

The 82.2% MLR versus the 82.7% consensus is further proof that the UnitedHealth has a handle on how to price premiums properly, she wrote in her note. "That this is not just a one-time event makes us even more comfortable that the driver of [UnitedHealth's performance] is the culmination of many factors," she said. "That UNH is years ahead of peers suggests that this could be a meaningful competitive and valuation advantage."

UnitedHealthcare added 2.5 Million covered individuals through employer and government sponsored offerings such as Medicaid and Medicare Advantage in the past 12 months.

Operations at the company's Optum unit, which offers pharmacy benefit management and healthcare analytics, grew 21%, with all Optum segments showing double-digit percentage earnings growth ].

Cash flows from operations were $2.2 billion in the quarter, up 29% year-over-year. Second-quarter net earnings of $2.32 per share were up 28% over second-quarter 2016. Adjusted net earnings of $2.46 were 26% higher year-over-year.

Despite Monday night's collapse of the latest Republican effort to repeal and replace Obamacare, analysts following UnitedHealth said they expect little effect on the company, largely because it has for all practical purposes withdrew from the Affordable Care Act health insurance exchanges for 2018.

"The company's exposure to the ACA business is essentially non-existent," wrote Oppenheimer & Co. analyst Michael Wiederhorn in a July 7 note addressing the uncertainty of the healthcare reform's fate.